We've had reports of SOS Collab Server "hangs" due to a bug in the Visual SourceSafe Automation component. SOS Collab uses this to communicate with the VSS database.

The following KB article refers to SOS Classic, but VSS issues are the same for SOS Collab. (SOS Collab should not have a problem with network cards, however, so you can disregard that part of the KB article.)